The answer is YES...if you have had sex even one time protected or not there is always the chance of pregnancy. When you factor being 3 days late and the throwing up in there it sounds more likely, still you may not be pregnant. You just went through a miscarriage a couple months ago and there is a chance your periods could be messed up and with all the business of the holidays and all the food going around there is a chance you could have just gotten sick from that, with all of this said though you have already gone through one pregnancy that carried to term and one that ended in miscarriage, that is a lot both physically and emotionally for your body to go through in the last year...by the way how is your little guy??? I don't know where you and your boyfriend are at with all the changes you have been through but have you thought about waiting to have sex again until your married?? I know everyone hates it when I say that but there is so much logic to it. I am pretty sure that 3 out of 10 (I could be wrong with the numbers) pregnancies ends in miscarriage, so try not to stress too much, if you are pregnant the stress alone could cause one even if your body is going to cooperate this time, I just want what is best for your family and it might be a good idea to practice abstinence until you are both ready to commit to marriage so that you are not putting yourself at risk for pregnancy and or more miscarriages, if you end up not being pregnant also think about your son, give him a little more time to be just him before having another baby, you are still young and healthy..I am sure you have plenty more baby making years, just take time to work on the family you have now and practice abstinence to assure not adding to it for a while longer....I hope this helps and if you go another week with a negative test then you should go get a blood test, I was 12 days late before I had a positive test this last time....let us all know...Love Meg